Virtual ballistic impact testing of Kevlar soft armor: Predictive and validated finite element modeling of the V0-V100 probabilistic penetration response

Abstract

This works presents the first fully validated and predictive capability to model the V0-V100 probabilistic penetration response of a woven fabric using a yarn-level fabric finite element model. The V0-V100 curve describes the probability of complete fabric penetration as a function of projectile impact velocity. The exemplar case considered in this paper comprises of a single-layer, fully-clamped, plain-weave Kevlar fabric impacted at the center by a 17-gr, 0.22 cal FSP or fragment-simulating projectile. Each warp and fill yarn in the fabric is individually modeled using 3D finite elements and the virtual fabric microstructure is validated in detail against the experimental fabric microstructure. Material and testing sources of statistical variability including yarn strength and modulus, inter-yarn friction, precise projectile impact location, and projectile rotation are mapped into the finite element model. A series of impact simulations at varying projectile impact velocities is executed using LS-DYNA on the fabric models, with each model comprising unique mappings. The impact velocities together with the outcomes (penetration, non-penetration) are used to generate the numerical V0-V100 curve which is then validated against the experimental V0-V100 curve. The numerical Vi-Vr data (impact, residual velocities) is also validated against the experimental Vi-Vr data. For completeness, this paper also reports the experimental characterization data and its statistical analysis used for model input, viz. the Kevlar yarn tensile strengths, moduli, and inter-yarn friction, and the experimental ballistic test data used for model validation. Keywords: Aramid fiber, Kevlar fabric, Impact behavior, Finite element analysis (FEA), Statistics, Probabilistic penetration